Culturing and colony data lab
Open your materials, follow the steps, then turn in your work.
Streak and incubate a culture, then count and describe colonies to gather data on bacterial growth.
1. Open your materials
Use the materials named in the first step below. Open lesson resources.
2. Start the work
Put on gloves and use aseptic technique to streak your plate.
Show all 6 required steps
- Put on gloves and use aseptic technique to streak your plate.
- Label the plate with your name, date, and sample, then set it to incubate.
- Once colonies grow, count the distinct colonies on your plate.
- Describe colony features: size, color, shape, and edges.
- Note any signs of contamination and separate them from your target colonies.
- Record your colony count and descriptions for analysis.
Lost your place? Lost your place? Find your step: if your plate is not streaked and labeled with name, date, and sample and in the incubator, finish that; if colonies have already grown, count the distinct target colonies, then describe each one's size, color, shape, and edge, and record any different-looking colonies as possible contamination.
Check your work before submitting
- You will be able to streak and incubate a culture aseptically.
- You will be able to count and describe bacterial colonies.
- You will be able to distinguish target colonies from contamination.
Before lab work: read the safety rules
- Goggles and gloves on before opening any culture tube; keep on until all materials are decontaminated.
- Treat all bacterial cultures as biohazardous even if the strain is labeled safe; apply standard BSL-1 precautions.
- Never open culture tubes near open flames or air vents; keep lids on except during inoculation.
- Flame inoculating loops until red-hot and allow to cool for five seconds before touching culture; do not wave hot loops through the air.
- Set plates to incubate inverted; do not stack more than three plates to prevent slipping.
- Before disposal: flood plates with 10% bleach, wait five minutes, then seal in biohazard bag for autoclave or dispose per school protocol.
- Wash hands with soap and water immediately after removing gloves.
3. Turn in your work
DueCheck Schoology- Hand in
- Colony data table: colony count, size estimate, color, shape, edge type for target colonies; separate tally for contamination colonies.
How to submit and name your file
Photograph plate and table; bring to Thursday's mutation and HGT analysis.
In Schoology, open your course and the assignment for this lesson. Attach your file, select Submit, and check that it appears in the submission.
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How this lesson connects
Keep using what you learned last class: Skin, breath, air, and unflamed tools all carry stray microbes, so aseptic technique limits their access to the plate in order to keep the culture pure and the results valid. Today: A streak plate isolates single cells so that each colony descends from one bacterium, which is why counting distinct colonies and describing consistent morphology gives you reliable data about a single strain.
Optional: listen or watch a unit review▸
Need help? Warm-up, timing, and directions▸
💡 Big idea: A isolates single cells so that each descends from one bacterium, which is why counting distinct colonies and describing consistent morphology gives you reliable data about a single strain.
- 0-8 minDon gloves and goggles; review Tuesday's checklist before opening any materials
- 8-25 minStreak the plate using the four-quadrant method (or as directed); use throughout
- 25-30 minLabel plate with name, date, and sample source; set to incubate inverted
- 30-52 minExamine incubated plates (pre-grown or same-day depending on protocol); count distinct colonies using a grid or tally method
- 52-67 minDescribe features in the : size (mm estimated), color, shape (round/irregular), and edge (smooth/rough/wavy)
- 67-80 minNote and separately count any colonies; record target- count and morphology summary
- • Every your doctor might prescribe was first tested against colonies grown exactly this way on agar plates.
- • The data you collect today, count and morphology, feeds directly into Thursday's analysis of how resistance spreads.
- • Your Tuesday practice has one job today: make sure what grows on your plate is what you intended to grow.
- • Exit goal: a labeled plate in the incubator and a complete description .
- • A isolates individual bacteria so each that grows represents one clone descended from a single cell.
- • morphology (size, color, shape, edge type) is a first-level identifier; consistent morphology across the plate is a sign of a .
- • colonies are identified by distinct morphology different from the target; their count is recorded separately but they are not included in target- analysis.
PLTW connection and today's work
Open Activity 1.2.3 Attack of the Superbugs in myPLTW and follow the culturing protocol to set up your plates today.
Today's stopping point: Pre-lab plan should be done (Tuesday); plates inoculated and documented today.
PLTW activity titles identify the course connection. If your account will not open, use the posted materials for today and tell Mr. Mendoza. Do not mark an online activity complete unless you completed it.
Course connection
- Project 1.2.3 Attack of the Superbugs
Use the turn-in directions at the top of this page. Do not create a second submission unless your teacher asks for one.
Show another explanation or a smaller first step
Need help? Choose a starting point
Finish the assigned lab safely before starting extra practice.
Lesson resources: reading, slides, and vocabulary▸
The deck carries the prior idea forward, lets you inspect an analogy, maps the rule to biology, and ends with the same evidence decision and exit ticket used on this page.
Generated from this lesson's canonical data with a red-team citation check.
Skin, breath, air, and unflamed tools all carry stray microbes, so limits their access to the plate in order to keep the pure and the results valid.
A isolates single cells so that each descends from one bacterium, which is why counting distinct colonies and describing consistent morphology gives you reliable data about a single strain.
An airport checkpoint uses an ID check, a metal detector, and an X-ray scanner.
- What can the ID check detect?
- What might set off the metal detector by mistake?
- Why do we need the X-ray if we already checked their ID?
A decision is stronger when the test fits the question and its limits are known.
Medical decisions also depend on biology, patient context, ethics, and professional judgment.
- • The ID check maps to confirming patient identity.
- • The metal detector maps to a rapid, non-specific screening test.
- • The X-ray scanner maps to a detailed, specific diagnostic test.
Driving question: You streak your plate today and incubate it. Tomorrow, how do you turn the dots that grow into a count and a set of descriptions that another scientist could check?
What you already know: Skin, breath, air, and unflamed tools all carry stray microbes, so limits their access to the plate in order to keep the pure and the results valid.
New idea: A isolates single cells so that each descends from one bacterium, which is why counting distinct colonies and describing consistent morphology gives you reliable data about a single strain.
Visual or model: F1. F1. A lesson illustration or teaching diagram for Culturing and colony data lab. Use it with E1-E3; it is a model or context image, not experimental or patient data. What to notice: Trace the labeled testing, treatment, or biological process and identify where evidence limits the decision.
- Observe or measure the relevant feature in today's lesson.
- Organize the observation with a stable evidence ID.
- Apply this rule: A decision is stronger when the test fits the question and its limits are known.
- Choose the option the evidence supports and state the limit of the conclusion.
Real biomedical example: You streak your plate today and incubate it. Tomorrow, how do you turn the dots that grow into a count and a set of descriptions that another scientist could check?
What the evidence supports: E1-E3 and F1 support the daily take-home when the response meets the stated success criteria.
What it cannot prove: The package does not support claims beyond this lesson's or any real patient diagnosis.
- • : A set of careful practices used to keep microbes out of a sterile area, protecting samples, cultures, and patients from .
- • : A population of microbes or cells grown on purpose in a nutrient medium so they can be studied, identified, or tested.
- • : A visible cluster of identical microorganisms growing on a plate, all descended from a single original cell.
- • : The slowing or blocking of a process, such as an stopping bacteria from growing or a molecule shutting down an .
- • : A change in the ; some change a enough to cause disease, many do not.
- • : The passing of genes between organisms, often bacteria, without reproduction, a major way resistance spreads.
Use it now: Choose one decision option. Cite E1 and E3, then explain how the rule connects the evidence to your choice.
Go further, optional: The source links below are optional enrichment. Every fact required for today's local evidence decision appears in this lesson package.
Laboratory depends on matching each identified hazard to an appropriate containment practice, protective measure, and stop-work condition before the procedure begins.
Limit: The lesson check does not replace the site-specific SDS, approved procedure, teacher supervision, or emergency plan.
A decision is stronger when the test fits the question and its limits are known.
Limit: Medical decisions also depend on biology, patient context, ethics, and professional judgment.
You can streak and incubate a aseptically.
Limit: E3 defines the classroom product or success criterion. It is not independent scientific evidence and cannot justify a clinical or causal claim.
PLTW-GEND-2026-10-05 · Simulated classroom evidence scenario
Your role: medical interventions team member
Decision: Your team must decide what the evidence from today's lesson supports before submitting the labeled and result claim named on today's page.
- • Restreak the plate before counting, because never spread the cells apart enough to give countable colonies.
- • Record only the separated dots that each grew from one cell, and log any off color as .
- • Count the biggest, densest patch as your strongest growth, since every colored spot on the plate is a .
Response: State one choice, cite at least two evidence IDs, explain the rule that connects them, and add one limitation. Submit it as the labeled and result claim.
Claim ceiling: Today's evidence supports a classroom claim about today's lesson. It cannot prove causation, diagnose a real patient, or justify action outside this room.
- • The solution must address the stated need in today's lesson.
- • The decision must be supported by E1-E3.
- • The final product must make the success criteria visible.
- • Complete the work inside the 80-minute block.
- • Use only supplied or teacher-approved materials and evidence.
- • Do not trade , accessibility, or privacy for speed.
- • and evidence quality: must pass before scoring other criteria.
- • User need and effectiveness: highest scored criterion.
- • Time, cost, and ease of use: compare only after and effectiveness pass.
Test evidence: For each option, record the E1-E3 result that supports or fails each criterion. Do not assign a score without a named observation.
- Version or option tested
- Criterion met or missed
- Evidence ID and result
- Revision made
- Reason for the revision
- Need and user
- Criteria and constraints
- Chosen option and evidence
- Test result
- Revision and reason
Students often think Students often think a bigger, denser-looking smudge on the plate means more or better colonies, and that any colored patch counts as a .. The trap: That is a trap because a smear where bacteria never got spread apart is , not countable colonies; you can only count where individual cells were isolated enough to grow into separate dots, and colonies that look different from your target (different color, shape, or edge) are and get recorded separately, not lumped into your count.
I streaked my plate using aseptic technique, labeled it with my initials, the date, and 'Sample 1,' and incubated it. After growth, I counted and described the colonies.
Target colonies: I counted 14 colonies that all looked the same, which suggests a pure culture descended from one strain. Each was small (about 1 mm), cream colored, round, and had a smooth edge.
Contamination: I found 2 colonies that looked different (larger, yellow, fuzzy edges). I did not count these as target colonies because they are a different organism. I recorded them separately so my analysis stays clean.
Conclusion note: Because almost all my colonies share one morphology, I am confident most of the plate is my target strain.
| Group | Count | Size | Color | Shape | Edge |
|---|---|---|---|---|---|
| Target | 14 | ~1 mm | cream | round | smooth |
| Contamination | 2 | ~3 mm | yellow | irregular | fuzzy |
This model shows the level of evidence and organization needed to complete: Completes the culturing lab data collection: a colony count with morphology descriptions for target colonies and a separate tally for any contamination colonies.
- Name the variables and include units.
- Enter observations without changing the raw values.
- Check labels, calculations, and patterns before interpreting the data.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
Also due today: Photograph your plate and table and bring them to the mutation and HGT analysis.
- CER:
- Claim, Evidence, Reasoning: make a claim, back it with evidence, explain your reasoning.
- SOP:
- Standard Operating Procedure, the exact steps to follow (especially in a lab).
- Tracker:
- Your PLTW progress log where you record completed evidence.
- myPLTW:
- The PLTW course site where you do the online activities. Find it in Clever with your Microsoft sign-in, right next to Schoology.
Tap the speaker to hear a term. Add two of these to your notebook glossary with a definition and an example in your own words.
Pick just 2 or 3 words from today and make them yours: write what each one means in your own words, name the context clue or evidence that helped, then give one example from what you actually did in Culturing and colony data lab. Try your own words first; the glossary is there if you get stuck. This is voluntary and counts as extra credit, so keep it short.
Saved on this device. Show Mr. Mendoza or add these to your notebook glossary to claim the extra credit.
Classroom documents for this lesson are posted in Schoology. Open Clever, then Schoology, and find each one by the name shown on its card.
Use this if you were absent, got stuck, or need another pass before you submit the lesson artifact.
Placement rationale
Matched Culturing, , superbugs by path:Medical-Interventions/Unit-1_How-to-Fight-Infection/00_Unit-Overview. Score 126. Visibility: student-schoology (student-facing resource; link through Schoology rather than local path).
Open this when the class reaches this activity and use it to complete the required lesson artifact.
Placement rationale
Matched Culturing, , superbugs by path:Medical-Interventions/Unit-1_How-to-Fight-Infection/1.2_-Treatment. Score 126. Visibility: student-schoology (student-facing resource; link through Schoology rather than local path).
Sign in to Clever with your district Microsoft account to open Schoology or myPLTW. Follow today's posted steps. If myPLTW will not open, use the posted alternative and tell Mr. Mendoza. Turn in your completed work through the Schoology assignment.
Practice: try a question, then check your answer▸
Claim ceiling for this check: Today's evidence supports a classroom claim about today's lesson. It cannot prove causation, diagnose a real patient, or justify action outside this room.
On your plate you count 24 round cream-colored colonies with smooth edges and 2 fuzzy green colonies. What is your target colony count, and what do you do with the green ones?
Write an answer and pick a confidence to unlock the key.
Fast retrieval with instant answers, not the commit-then-reveal check above. Try each from memory first: write what you remember about the earlier units, then check yourself here.
Missed class or ready for more?▸
Run this before you touch the bench. It is built from the real lab procedure, so the decisions you make here are the ones you will make with the equipment in your hands.
I can name the procedure's purpose and the evidence I will record. I can name today's hazards and the control for each: Goggles and gloves on before opening any culture tube; keep on until all materials are decontaminated. My data table is ready before materials are handled.
Finish the checklist before you handle any material.
- • Goggles and gloves on before opening any culture tube; keep on until all materials are decontaminated.
- • Treat all bacterial cultures as biohazardous even if the strain is labeled safe; apply standard BSL-1 precautions.
- • Never open culture tubes near open flames or air vents; keep lids on except during inoculation.
- • Flame inoculating loops until red-hot and allow to cool for five seconds before touching culture; do not wave hot loops through the air.
- • Set plates to incubate inverted; do not stack more than three plates to prevent slipping.
- • Before disposal: flood plates with 10% bleach, wait five minutes, then seal in biohazard bag for autoclave or dispose per school protocol.
- • Wash hands with soap and water immediately after removing gloves.
- 1Before materials are handled, identify the purpose, variables or comparison, controls, measurement units, and stop-work condition.
- 2Put on gloves and use aseptic technique to streak your plate.
- 3Label the plate with your name, date, and sample, then set it to incubate.
- 4Once colonies grow, count the distinct colonies on your plate.
- 5Describe colony features: size, color, shape, and edges.
- 6Note any signs of contamination and separate them from your target colonies.
- 7Record your colony count and descriptions for analysis.
- 8Record each result in the prepared table before interpreting it. Mark missing, repeated, or invalid results truthfully.
- 9Complete the named cleanup and waste route, remove PPE safely, wash hands when required, and confirm the station is ready for the next group.
| Trial or sample ID | Independent condition | Measured result with units | Observation before interpretation | Quality-control note |
|---|---|---|---|---|
Before the procedure, predict the result and cite the rule behind the prediction.
After the procedure, compare the result with the prediction and name one limitation or source of uncertainty.
What today's skills lead to. These are real health-science careers this course builds toward. Tap one to see, on the US Department of Labor's O*NET site, what the job actually involves, what it pays, and how fast it is growing.
If you miss the lab, work the virtual resistance dataset and teacher images: count colonies, describe their features, and submit your .
learn.genetics (Utah) virtual labsPhotograph plate and table; bring to Thursday's mutation and HGT analysis.
Class still runs. Complete the online activity above (it's self-guided). Need the concept taught without a teacher? Use this authoritative explainer:
CDC Antibiotic Resistance- CompleteEvery required part of the artifact is present, nothing left blank.
- AccurateThe science and the data are correct and match the evidence.
- Scientific reasoningYou explain your claim with evidence and reasoning (CER), not just an answer.
- Professional communicationClear, organized, labeled, and written the way a clinician or scientist would.
- SubmittedGo to Schoology to turn this in. Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf. If you cannot get in, see Mr. Mendoza. Do not skip the work.
- Error analysis and method · counts doubleName a specific limit of the method and how it moved your result, and compare what you predicted to what happened. "Human error" does not count; say what about the procedure or instrument caused it.
This week
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